Refillable electric fuse



Jan. 10, 1928. 1,656,121

F. C. LA MAR REFILLABLE ELECTRIC FUSL Filed 'Dec 1 1924 Patented Jan. 10, 1928.

UNITED STATES 1,656,121 PATENT- OFFICE.

' FRANK C. LA MAR, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO GREAT WESTERN FUSE COMPANY, INC., 015 PITTSBURGH, PENNSYLVANIA, A CORPORATION 01 DELAWARE.

REFILLABLE- ELECTRIC FUSE.

Application filed December 1, 1924. Serial No. 753,310.

causing fires, when-the fuse is subjected to.

an overload or excess of currentand the fuse element blown or burned out, the construction being such that the hot gases due to the.

explosion or burning out of the fuse element, are effectively confined within the shell or casing and become cooled therein and eventually slowly escape therefrom through the restricted passages provided therefor in the construction of the fastening means for securing the fuse element and the terminal contact member in the ends of the 26 casing or shell constituting the present invention.

The invention consists in a refillable fuse, comprising a shell or casing of fibre or other insulating or refractory material, metallic 30 end ferrules fitted upon the ends of the shell or casing having exteriorly screwthreaded ends and inwardly projecting diametrically opposite lugs or seats and intervening spaces, a fuse element, and endte'rminals to which the fuse elementis connected, an elongated plate or washer fixed to theend terminals and adapted to seat upon said inwardly projecting lugs or seats in said ferrules, locking washers fitted upon said end 40 terminals and seating against said elongated plates or washers and engaging said ferrules to hold said end terminals in alinement, and a screwthreaded cap fitted upon the ferrules for forcing and holding said locking washer and end terminals in. place.

The invention also consists in other certain details of construction, combination and arrangement of parts, all. substantially as I will proceed now more particularly to set forth and finally claim.

In the accompanying drawings, illustratthrough the shell or casing, and showing the end terminal and fuse element on the right hand side in full lines, and on the left hand side in dotted lines. Fig. 3 is an end view, with the end cap partly broken away to show the washer fitted upon the end terminal. Fig. 4 is an endview with the end cap and outside washer removed and showing the locking washer fitted upon the end terminal. Fig. 5 is an end view with the end cap, outside washer and locking washer re-' moved, and showing the end terminal and elongated plate or washer fixed thereto seated upon the inwardly projecting lugs on the end ferrule. Fig. 6 is an end view of the shell or casingywith the end terminals and fuse element removed. Fig. 7 is a detail VleW, showing the locking washer in bottom plan view and edge View.

In the drawings, the invention is shown as :applied to a refillable or renewable fuse of the knife-blade type, and 1 indicates the body of the shell or casing, of fibre or other suitable insulating or refractory material, and provided at its ends with reduced exteriorly screwthreaded portions 2, and fitted upon said screwthreaded ends of the casing or shell are metallic ferrules 3 having their outer ends reduced and projecting beyond the ends of the casing and provided with exterior screwthreads, as at 4, adapted to receive interiorlyscrewthreaded ring-shaped end caps 5, having inwardly extending flanges 5', for a purpose "hereinafter described.

The ferrules 3 are provided near their outer ends, and beyond the edge thereof,

.with a series of inwardly projecting and diashanks 10 of the'knife-blade' terminals 11, by

means of screws 12 in the usual manner.

' ing the invention, in the several figures ofe" In accordance with this invention, the end which like parts are similarly designated,

Figure 1 is a side elevation of the assembled 66 fuse. Fig. 2 is a longitudinal section,

terminals or knife-blades 11 are provided with an elongated metallic plate or washer 13, and in the preferred construction, and as herein shown, said elongated plate or washer 13 is constructed of a piece of metal of a width considerably wider than the thickness of the knife-blades or terminals 11, so as to project from the sides thereof, and of a length substantially equal to the width of the knife-blade or terminal 11, and is provided with a longitudinal slot, as shown in 'dottedlines Fig. .5, whereby the said plate washers 13, are curved, as at 14, Fig. 5, to coincide with the curved wall 15 of the ferrule above the seats or lugs 6 to fit closely,

therewith when the fuse is assembled, for a purpose hereinafter described.

16 is a lock washer, having a central elongated slot 17, and a pair of teats or lugs 18, preferably struck up from the metal of the washer, and arranged upon each side of said slot and parallel therewith, thesaid washer being adapted to be slipped upon the knifeblade 11 with its lugs or teats 18 engaging the grooves 8 in the end of the ferrule 3 in assembling the fuse.

19 is a plain washer having a central elongated slot 20, and adapted to be fitted upon the knife-blade .and rest 'upon the lock washer 16, in assembling the fuse, and forced to lace bythe end ca 5.

n assembling the e, the fuse, element 9 is attached to the shanks 10 of the end terminals or blades'12, and one of the terminals or blades is then inserted endwise into the end of the casing, the elongated plate or washer Iii-carried by the terminal or blade being alined with either of the two diametrically opposite spaces 7 in one end of the-ferrules, as indicated in dotted lines Fig. 5, and passed through the casing and through the alined two diametrically opposite spaces 7 between the lugs 6 on the ferrule at the other end-of the casing, and just beyond the lugs 6. The knife-blades or terminals and attached fuse element are then given a quarter turn, in either direction, and the ends of the elongated plates or washers 16, 13, brought over and upon apair of the diametrically opposite lugs or seats 6, as shown in full lines Fig. 5, and at the right of Fig. 2, the curved edges of the plates or washers fitting closely the inner curved edges j of the ferrules adjacent to the lugs 6, and the outer surfaces of the plates or'washers exding a slight distance beyond the outer edges of the ferrules, as shown atthe right,

Fig. 2. The locking and alining washers 16 are then slipped upon the knife-blades and forced up against the plates or washers 13 and the lugs or teats 18 thereof positioned in the ends of the grooves 8 upon opposite sides of the lugs or seats 6 unoccupied by the plates or washers 13 andon opposite sides of the said plates or washers, thereby holding and lockingthe plates or washers 13 in place upon the lugs or seats and maintaining the knife-blades or terminals in alinement. The plain washers 19 are then slipped upon the knifeblades and brought close up to the locking washers 1S, and the ring-shaped end caps 5 fitted upon the ends of the ferrules and screwed to place, the inwardly projecting flanges" 5 thereof engaging the washers 19 and forcing the locking washers to place and against the sides of the elongated plates or washers 13,

and thus firmly bringing said parts together,

and efl'ectinga sufficiently tight or sealed joint between the parts at theends of the casing to prevent the escape of the hot gases or products of combustion due to the-burning out of the fuse'element on an overload or excess of current passing therethrough, but

still affording a very restricted passage for the gases-of combustion, thereby maintaining such gases within the casing until they become cool and which will gradually escape through such restricted passages and thus avoid bursting of the casing when a fuse is burned out by an overload of current.

In order to permit the ready assemblage ofthe parts of a fuse of this'construction, the fuse element is made ofrjust sufficient length so that when connected to. the end terminals or knife-blades, and inserted in the casing, as hereinbefore described, the elongated plates or washers 13 on the-terminals at both ends of thecasing will be ferrules and the outer surfaces thereof beyond the ends of the ferrules,-to permit the ready adjustment of the terminals to effect their alinement with the seats or lugs 6 and to be engaged by the-washers for forcing the casing are constructed of metal, the parts being so constructed and arranged rela- .slightly beyond the seats or' lugs 6 on the tivel to one another in the assemblage of the 'e, as to effect a practicallyair and gas tight seal between the coacting parts and still'leaving a 'sufiicient but restricted. pasi sage for the escape of the gases of combus tion due to a blown-out fuse, after becoming cooled by being retained in the casing, and

without the use of felt or other combustible washers for sealing the ends of fuses of this sort, as has heretofore been done, for the purpose of making fuses of this sort proof against danger of causing fires.

It will be understood that the invention is not limited to the exactdetails ofconstruction, combination and arrangement of parts herein shown and described, as the same may be changed in various particulars, and still be within the scope of the claims herein. A

What I claim is: a

1. A refillable electric fuse, comprising a casing, having diametrically opposite inwardly projecting seats and intervening spaces at its ends, end terminals havin elongated plates fixed thereto, a fuse e ement connecting said end terminals, the said fuse element and its attached end terminals adapted to be assembled in said casing by passing one of the end terminals and its attached elongated plate through the casing and through two of the diametrically opposite spaces between the seats in the ends of the casing and turning the terminals to bring the plates thereon 'into'alinement with the outer faces of two of the diametrically opposite seats at bothends of the casing, and means applied to the ends of the casing and engaging the terminals and plates to lock and aline said terminals and plates in said casing and upon said seats.

2. refillable electric fuse, comprising a casing of insulating material, externally screwthreaded ferrules fixed 'to the endsof said casing and provided with diametrically opposite inwardly projecting seats and in-- tervening spaces adjacent to their outer ends, end terminals having elongated plates fixed thereto," a fuse element connecting said end terminals, the said fuse element adapted to be assembled lengthwise ,into' said. casing through the intervening spaces between said seats with the ends of the attached elongated plates engagin the outer surfaces of two of the diametrica ly ppposite inwardly projecting seats in said ferrules, and locking washers fitted upon said terminals and engagin the elongated plates and said ferrules, .an end caps screwthreaded upon said ferrules for forcing said locking washers against said elongated plates to hold the plates upon said seats.

3. A refillable electric fuse, comprising a casing of insulating material, externally screwthreaded ferrules. fixed to the ends of said casing and provided-with diametrically opposite inwardly projectin seats and in tervening' spaces adjacent to t eir outer ends, knife-blade terminalshaving elongated plates fixed thereto and having their ends with said seats, and rin shaped end caps screwthreaded upon said errules and adapted to exert pressure upon said locking washer to hold the parts in place.

4, A refillable electric fuse, comprising a casing of insulating material, externally screwthreaded ferrules fixed to the ends of said casing and provided with diametrically opposite inwardly projecting seats and intervening spaces ad acent to their outer ends,

knife-blade terminals having elongated plates fixed thereto and having their ends coinciding with the edges of the knife-blade terminals, a fuse element connecting vsaid knife-blade terminals, the said fuse element and its attached terminals and plates adapted to be assembled lengthwise into said casin through the intervening spaces between sai seats with the ends of the elongated plates engaging the outer surfaces of two of thediametricall opposite inwardly rojecting seats in sai ferrules, locking was ers fitted upon said knife-blade terminals and engaging the elongated plates thereon and provided'with inwardl projecting lugs adapted to engage the ferru es upon opposite sides of said seats to hold the elongated plates in alinement with said seats, washers fitted upon said knife-blade terminals and engaging the locking washers, and ring-shaped end caps screwthreaded upon said ferrules'and enga in said last-named washers, to force and 01 the elongated plates and washers inplacep. F 5. A refillable electric fuse, comprising a casin ofinsulating matenal, externally sore hreaded metallic ferrules fixed to the ends of said' casing and rovided with diametrically opposite inwar y projecting seats and intervening spaces ad acent to their outer ends, and grooves in said ferrules on the opposite sides of said seats, end terminals having elongated plates fixed thereto, a fuse element connecting said end. terminals, the fuse element and its attached end terminals adapted to be assembled lengthwise into said to, hold said elongated plates in alinement too grooves in "said ferrules upon opposite sides of said seats for holding said elongated plates in alinement with said seats, and end 7 v gaging said elongated plates and provided caps screwthreaded upon said ferrules for forcing said locking washers against said elongated plates to hold the plates upon said seats.

6. A refillable electric fuse, comprising a casing of insulating material, metallic end ferrules fixed to the ends of said casingand provided with inwardly projecting diametrically opposite seats and intervening spaces,

and knife-blade terminals having elongated plates fixed thereto and projecting from the sides of said terminals and having their ends curved and substantially flush with the edges of the terminals, a fuse element connecting the knife-blade terminals, the said fuse element and its attached terminals and elongated plates adapted to be assembled lengthwise in said casing through the intervening spaces between said seats and turned to cause the elongated plates on said ter-' minals to aline with the outer face of said seats, with their curyed ends coinciding with the curvature of the inner walls of the ferrules ad'acent tosaid seats, locking and alming was ers fitted on said terminals and enwith lugs for engaging the ferrules, and ring-shaped end caps screwthreaded upon said ferrules for forcing said washers against the elongated plates to hold said plates against said seats.

' 7. A refillable electric fuse, comprising a I casing of insulating material, metallic end ferrules fixed to the ends of said casing and provided with inwardly projecting seats, a-

fuse element, plates connected to the terminals of the fuse element and fitted to the ends of the ferrules and engaging the outer faces of the inwardly projecting seats thereof and projecting beyond the ends of the ferrules, and a screw cap fitted. upon said ferrules adapted to exert pressure upon said,

plates to hold them in place upon said seats;

In testimony whereof I hereunto ailix my signature.

, 'FR'ANK'C. LA MAR. 

